Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ky dang » ky nang, ky danh
dang ma » dang mau, dang mam, dang mat
van cam » van nam, van lam, van cau
tai cuu » tai cuc, tai buu, tai cua
cuu tre » cua tre, cau tren, cau treo
luc va » tuc va, loc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky dang ma hoa. hieu van cam ((luc va) or (duc va)) doanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky dang ma hoa. hieu van cam ((luc va) OR (duc va)) doanh tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky dang ma hoa. hieu van cam ((luc va) or (duc va)) doanh tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky dang ma hoa. hieu van cam ((luc va) or (duc va)) doanh tai cuu tre*.